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D A Gilbert

Publications and source records attributed to D A Gilbert.

At least 37 records · Page 2Linked to original sources
PubMed1995

Approach to genotyping errors caused by nontemplated nucleotide addition by Taq DNA polymerase.

Thermostable DNA polymerases can catalyze nontemplated addition of a nucleotide to the 3' end of amplification products. This presents a potential source of error in genotyping studies employing Taq DNA polymerase to amplify microsatellite loci. Although the activity is marker specific, experimental variation is often seen in the degree of modification. Consequently, for a given microsatellite marker, an allele may be inconsistently identified as either the unmodified or modified amplification product. Full automation of high-throughput genotyping has been hampered by the need for manual editing of data because of this source of allele misidentification. In this study we estimate a 1% to 3% error rate attributable to nontemplated nucleotide addition in the ABI PRISM genotyping system. We present a PCR-based strategy to minimize this source of error.

Alleles↗
PubMed1995

Elderly residents: perceptions of nurses' comforting touch.

1. Elderly nursing home residents often feel unwanted or unloved because of a lack of physical contact with others or their caregivers' inability to communicate love and belonging. 2. In a study of 25 elderly nursing home residents, it was found that those who were subjected to comforting touch by their nurses perceived an increased feeling of affection and immediacy. 3. The conscious and intentional use of comforting touch by nurses and caregivers to elderly nursing home residents should be encouraged because of its beneficial effect of conveying love and belonging.

Aged↗
PubMed1994

Oscillatory variations in the amount of protein extractable from murine erythroleukemia cells: stimulation by insulin.

The amount of protein extractable from murine erythroleukemia (MEL) cells varies in an oscillatory manner at high frequency and high amplitude as it does for several other cell lines. Moreover, the rhythm appears to be modulated in periodic fashion with respect to the mean, period and amplitude. The phenomenon thus seems to be universal and fundamental. Time series analyses support the view that several periodicities contribute to the observed protein rhythm. Insulin affects the dynamics as it does for both morphological and phosphorylation oscillations. Caution is necessary in the interpretation of 'specific activities' of cellular components and in electrophoretic studies wherein equal amounts of protein are applied to the wells in an effort to correct for random errors.

Animals↗
PubMed1994

Insulin stimulation of high frequency phosphorylation dynamics in murine erythroleukemia cells.

The phosphorylation potentials of two proteins (M(r) 81 kDa and 63 kDa) in extracts of murine erythroleukemic (MEL) cells both vary in an oscillatory manner, sometimes changing by as much as 100-fold in 10 min. Direct analysis of the temporal changes indicates the existence of periodic modulation of the frequencies, amplitudes and mean levels of the two rhythms. In both cases, periodogram analyses, by two methods, confirm the presence of several oscillations having periods in the range 20-100 min which tend to occur in (pseudo) periodic bursts. Insulin has been found to enhance these oscillations in a manner comparable with its effect on rhythmic variations in cell morphology. Despite the marked similarity in the behaviour of the two proteins, no particular phase relationship existed between the two temporal variations, suggesting differences between the underlying driving forces.

Activity Cycles↗
PubMed1994

Penile prosthesis implantation in total phalloplasty.

A series is presented of 8 patients who had undergone either total phalloplasty or free flap penile reconstruction. Our experience with prosthetic implantation is reviewed as is a brief history of phallic construction, including previously reported efforts at achieving rigidity with prosthetic implantation, autologous material implantation and so forth. We present in detail our current technique of implantation in these 8 patients, who underwent 10 attempts at implantation. In 4 patients infection necessitated removal of the prosthesis (2 have since undergone successful reimplantation). Of the 8 patients in whom implantation was attempted 6 (60%) currently have prostheses in place.

Adolescent↗
PubMed1993

Insulin-induced enhancement of cell morphological dynamics: non-specific biophysical mechanisms for the generalized stimulation of metabolism?

Time series analysis of fluctuations in the intensity of light scattered by cells indicates the existence of a range of oscillations in cell morphology that usually occur in (pseudo) periodic bursts. Insulin has a frequency-dependent effect on the rhythms, predominantly that of stimulating the short period components believed to reflect surface movements. It is suggested that the non-specific action of the hormone on transport is due to an effective decrease in the net thickness of the surrounding diffusion layer (resulting from increased stirring of the micro-environment) and to accompanying membrane and cytoplasmic vibrations. From published data it seems likely that other mitogens and chemotactic agents act in a similar manner.

Animals↗
PubMed1993

Repair of the complications of hypospadias surgery.

In 1992 a retrospective review was conducted of 190 patients evaluated and treated for complications of hypospadias surgery during 1979 through 1990 at the Devine Center for Genitourinary Reconstructive Surgery of Sentara Norfolk General Hospital and Children's Hospital of the King's Daughters. We could not contact 13 patients and 8 are awaiting a second stage procedure. Of the 177 patients 167 (94.35%) have had a successful outcome, defined as a controllable urinary stream, functional erection and an acceptable cosmetic appearance, and 2 (1.13%) are considered failures. Details of presenting problems, surgical techniques and recent modifications of these procedures are presented.

Adolescent↗
PubMed1993

Phallic construction in prepubertal and adolescent boys.

During the last 10 years we performed microsurgical phallic reconstruction in 7 prepubertal and 4 adolescent boys. Indications for surgery included post-traumatic amputation, circumcision accident, developmental anomalies and micropenis. In addition, we performed phalloplasty on 5 other patients 18 to 24 years old. Total phallic reconstruction consisted of 1-stage microsurgical tissue transfers that included urethral reconstruction, coaptation of erogenous nerves, aesthetic refinement and, in some cases, scrotal reconstruction. All postpubertal patients recovered erogenous sensibility in the reconstructed phallus and the ability to masturbate. Surgical indications, techniques and results are discussed.

Adolescent↗
PubMed1992

Molecular phylogenetic inference from saber-toothed cat fossils of Rancho La Brea.

A method for the successful extraction of sequestered cellular DNA from 14,000-year-old fossil bones was developed and applied to asphalt-preserved specimens of the extinct saber-toothed cat, Smilodon fatalis. Two distinct gene segments, the mitochondrial gene for 12S rRNA and nuclear FLA-I (the feline class I major histocompatibility complex gene), from three different individual fossil specimens were cloned and sequenced after PCR amplification. Comparison of fossil-derived DNA sequences to homologous regions in 15 living carnivorous species, including 9 species of Felidae and 6 nonfelids, affirmed the phylogenetic placement of Smilodon within the modern radiation of Felidae distinct from the Miocene paleofelid (Nimravidae) saber-toothed "cat" species. These results raise the prospect of obtaining genetically informative DNA from preserved bones of extinct fossil species, particularly among the 2 million specimens excavated from the asphaltic sediments at Rancho La Brea in metropolitan Los Angeles.

Animals↗
PubMed1992

Estimation of heterozygosity for single-probe multilocus DNA fingerprints.

In spite of the increasing application of DNA fingerprinting to natural populations and to the genetic identification of humans, explicit methods for estimation of basic population genetic parameters from DNA fingerprinting data have not been developed. Contributing to this omission is the inability to determine, for multilocus fingerprinting probes, relatively important genetic information, such as the number of loci, the number of alleles, and the distribution of these alleles into specific loci. One of the most useful genetic parameters that could be derived from such data would be the average heterozygosity, which has traditionally been employed to measure the level of genetic variation within populations and to compare genetic variation among different loci. We derive here explicit formulas for both the estimation of average heterozygosity at multiple hypervariable loci and a maximum value for this estimate. These estimates are based upon the DNA restriction-pattern matrices that are typical for fingerprinting studies of humans and natural populations. For several empirical data sets from our laboratory, estimates of average and maximal heterozygosity are shown to be relatively close to each other. Furthermore, variances of these statistics based on simulation studies are relatively small. These observations, as well as consideration of the effect of missing alleles and alternate numbers of loci, suggest that the average heterozygosity can be accurately estimated using phenotypic DNA fingerprint patterns, because this parameter is relatively insensitive to the lack of certain genetic information.

Animals↗
PubMed1992

Microsurgical forearm "cricket bat-transformer" phalloplasty.

Presently, the donor flap of choice for microsurgical phallic reconstruction is the radial forearm flap. The success of several different design modifications confirms the reliability of the radial and ulnar forearm flaps. Farrow et al. described their experience with the "cricket bat" concept in 1980. To the previous "cricket bat" design, we now wish to add modifications. These modifications utilize longitudinal and transverse rotations of the linear forearm tissues to create a phallus--much like the transformation of a toy robot into a truck. Deepithelialized flaps and a full-thickness skin graft coronoplasty complete glans reconstruction. The "cricket bat-transformer" flap appears to produce the most predictable results in subtotal phallic reconstructions and phallic constructions in the pediatric and transgender patient groups.

Adult↗
PubMed1991

The surgical treatment of chordee without hypospadias in men.

During a 2-year period we treated 26 young men for chordee without hypospadias. Many of these patients had straight erections as children but a ventral curvature developed as they achieved puberty. We describe the anatomical findings and discuss the possible cause for the development of this anomaly. Surgical therapy begins with a circumcising incision and reflection of the skin to expose the shaft of the penis. The corpus spongiosum containing the urethra was mobilized by resecting the dysgenetic tissue in the dartos and Buck's fascia layers. In 1 patient this dissection was sufficient to straighten the penis but in the remaining 25 the penis was not straight. In those patients we mobilized the dorsal bundle of vessels and nerves, and removed 1 or several ellipses of tunica albuginea to equalize the lengths of the ventral and dorsal aspects of the corpora cavernosa. The corpus spongiosum usually is elastic and the curve almost never is caused by shortness of the urethra, which stretches to fit the straightened penis. In 24 of the 26 patients the curvature was resolved with 1 operation, while 2 needed a second procedure.

Adolescent↗
PubMed1991

In vitro inhibition of hepatitis B virus replication by 2',3'-dideoxyguanosine, 2',3'-dideoxyinosine, and 3'-azido-2',3'-dideoxythymidine in 2.2.15 (PR) cells.

Hep G2-derived hepatoblastoma cells (2.2.15), which actively produce hepatitis B virus (HBV), were cultured in the presence of 2',3'-dideoxyguanosine (ddG), 2',3'-dideoxyinosine, or 3'-azido-2',3'-dideoxythymidine (AZT). ddG was the most potent agent. It diminished viral replication by up to 95%, as assessed by the amount of episomal HBV DNA, without impairing cellular growth. AZT was the least effective against HBV. Northern blot analysis revealed no apparent difference in the pregenomic viral RNA profile, suggesting that these dideoxynucleosides suppress reverse transcription in the replicative cycle of HBV. The effect of varying the time of drug exposure showed that these agents can suppress HBV replication even when added late in culture. HBV replication in another 2.2.15 cell population of the same lineage was affected by ddG differently, which may enable the investigation of phenotypic or genetic alterations during culture. The present data suggest that some 2',3'-dideoxynucleosides can exert a potent antiviral activity against HBV in vitro, at least under certain circumstances, although the data do not prove that any of these agents have utility in patients with hepatitis.

Blotting, Southern↗
PubMed1990

Oscillations in cell morphology and redox state.

Fluctuations in the intensity of light scattered and absorbed by cells in suspension have been analysed by smoothing, periodogram and power spectrum methods to reveal oscillations attributed to changes in cell morphology and the redox state of NADH and FAD (periods 10 s to 30 min). The rhythms are themselves periodically modulated in amplitude at a similar frequency and exhibit burst characteristics. The low frequency scatter dynamics are provisionally attributed to oscillations in gross morphology and the high frequency variation to changes at the cell surface. Agents, such as insulin and transferrin, affect the dynamics. The scatter results suggest that rhythmic changes in cell morphology associated with locomotion are largely inherent in the cell and not due to periodic attachment and detachment from a surface.

Animals↗
PubMed1990

Genetic fingerprinting reflects population differentiation in the California Channel Island fox.

Restriction fragment profiles generated by hybridization of hypervariable minisatellite DNA probes have been used for paternity analysis but not for comparisons at the level of populations, because the profiles are thought to evolve too rapidly to be informative over large time intervals. But in small isolated populations, the fixation of restriction-fragment polymorphisms can outpace the generation of fragment-length variability through recombination. Here we report on an analysis of DNA fingerprints of the California Channel Island fox (Urocyon littoralis). These foxes comprise an island dwarf species found only on six of the Channel Islands off the coast of southern California. Variability of restriction-fragment profiles within fox populations, as indicated by the average percentage difference (APD), varied widely among the islands, from 0.0% (no variation) to 25.3%. The APDs between populations were considerably greater (43.8% to 84.4%). In addition, foxes on each island can be distinguished by the presence of diagnostic restriction fragments. Maximum parsimony and phenetic trees relating foxes from different islands are consistent with the archaeozoological and geological record. Therefore, in small populations of genetically isolated mammals, differences among hypervariable restriction-fragment profiles can be used to estimate relative genetic variability and to reconstruct the evolutionary relationships of natural populations.

Animals↗